1. Field of the Invention
The present invention relates to a vehicle for traveling on uneven terrain, and more particularly to a saddle-type four- or three-wheel vehicle or the like.
2. Background Art
Ground contact pressure (load per tire/ground contact area) (kg/cm2) is an important factor in traveling on a road surface having a small friction coefficient (xcexc), such as a muddy, marshy, sandy, snowy, or graveled road surface.
The ground contact pressure of a general passenger car is normally within the range of 1.8-2.3 kg/cm2. Therefore, traveling on a soft road having a small friction coefficient (xcexc) in such a passenger car results in significant tire sinking as well as road surface grip deterioration, especially in a road surface having small protrusions such as a gravel road surface which degrades traveling performance.
Therefore, a vehicle fitted with low-pressure balloon tires, having small ground contact pressure, has been suggested for traveling on uneven ground as described above. The ground contact pressure of the aforementioned low-pressure balloon tire is approx. ⅕th that of the passenger car, i.e. no more than 0.50 kg/cm2.
FIG. 1 is a graphical view showing the relationship between torque transmission time (abscissa axis) and torque transmitted to a drive shaft (ordinate axis) of a vehicle traveling on uneven ground fitted with the low-pressure balloon tires. In FIG. 1, a dotted line (b) shows the relationship for a conventional vehicle traveling on uneven ground and equipped with a manual transmission (MT).
As seen in FIG. 1, when the manual transmission (MT) is switched from a neutral to a low position, a significant torque variation is experienced that often exceeds a slip limit of the tire. This occurs even though the vehicle is fitted with low-pressure balloon tires having small ground contact pressure.
The present invention overcomes the shortcomings associated with the related art and achieves other advantages not realized by the related art.
An aspect of the present invention is to provide a vehicle for operating on uneven terrain having reduced power transmission creep, improved slip functionality, and smooth power transmission.
An additional aspect of the present invention is to provide smooth power transmission and creep reduction can be accomplished in a idle speed or neutral gear train setting.
These and other aspects of the invention are accomplished by a vehicle for traveling on uneven terrain comprising low-pressure balloon tires, and a power unit having an engine and a multistage transmission, wherein a torque converter is provided in a power transmission path extending from an engine crankshaft to a multistage transmission input shaft.
These and other aspects of the present invention are further accomplished by a vehicle for traveling on uneven terrain comprising a plurality of low-pressure balloon tires; a vehicle body having a longitudinal direction and a transverse direction; and a power unit having an engine and a multistage transmission, wherein a torque converter is provided in a power transmission path extending from an engine crankshaft to a multistage transmission input shaft, the engine crankshaft arranged in parallel with the longitudinal direction of the vehicle body.
Further scope of applicability of the present invention will become apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.